Is dyslexia a vague term?

“The symptoms of dyslexia vary from person to person which seems to justify the belief of many in the educational system that dyslexia is a vague term. It is true that no two persons’ experiences with dyslexia are exactly the same and this is due to an individual’s strengths compensating for the individual’s weaknesses. Not only does this make the identification of dyslexia difficult, but there is no single test or score that identifies dyslexia.
The key identifier of dyslexia is unexpected in relation to an individual’s ability. The general pattern of dyslexia is average to above average in understanding concepts but low in skills. Dyslexia becomes more apparent when looking at the patterns of errors and difficulties.”